NASA Delves Into Mysteries of Mercury’s Magnetic Fields

At one point in time in the past couple billion years, Mercury possessed a magnetic field that was as strong, or possibly stronger, equal to Earth’s. The researchers at NASA will delve into the mystery with more focus now that their MESSENGER spaceship has crashed into the planet’s surface. The data from the downed spacecraft have opened up new possibilities that Mercury has evolved, according to NASA scientists.

Mercury is the smallest known planet, as well as the planet closest to the center of the solar system. Being so close to the Sun, studying it has been problematic for years. However, MESSENGER became the first space probe to enter into an orbit around Mercury, whereas other spacecrafts had to make flyby reports of the planet’s surface and atmosphere, such as by NASA’s Mariner 10 around 40 years ago. MESSENGER’s orbiting mission was ended when it crashed into Mercury’s surface.

When the Mariner 10 performed its flyby mission, it recorded that at the time, Mercury possessed a magnetic field that only generated strength about 1/100th the strength of Earth’s ones. However, it generates its magnetic fields in the same way that Earth does, with the swaying of liquid metal residing in the core of the planet. Mercury and Earth are the only terrestrial planets with that type of magnetic resonance system.

Catherine Johnson, a planetary geophysicist from the University of British Columbia, said that this means Mercury’s core is at least comprised of liquid to some degree. She told Space.com that it was a big surprise because a planet of Mercury’s size would normally have a core that could be cooled in a haste, rendering it completely solid. Although, if Mercury’s core is not pure metal, than it would possess a lower freezing point, making it much harder for its core to become 100 percent solid.

The information transmitted back to NASA by MESSENGER left a few clues about the mystery surrounding the planet’s fluctuating magnetic field strength, and NASA scientists are sure to delve into the information soon. The MESSENGER spacecraft was launched in 2004, then it spent over a decade traveling to Mercury. Once in the terrestrial planet’s orbit, the probe delivered immeasurable amounts of data. The probe ran low on fuel and crashed into the planet, and the NASA officials believe it left a nasty 52 foot scar along the planet’s surface.

NASA researchers combed through and analyzed the data gathered by MESSENGER in the later months of 2014, and earlier in 2015, as well. The data scrounged up in that stretch of time was when the space probe orbited the planet as low as nine miles above the planet’s surface. The lowest recorded height off of Mercury’s surface before then was between 125 and 250 miles.

Johnson stated that the magnetic signals they could detect in the data were rather small, and incredibly difficult to measure accurately. If MESSENGER had not relocated to it’s nine mile position, the team would never have been able to understand their findings at all. The magnetic resonances came from a part on Mercury that is still heavily cratered, most likely from older meteor impacts, suggesting that those parts of the planet are more ancient and untouched. The source of the resonances came from rocks that scientists measured to have produced magnetic fields for close to four billion years.

Johnson said that if NASA can pinpoint exactly how long Mercury’s possessed thriving magnetic fields, that will help them to delve into the mystery of the planet’s history. Thus, scientists will learn more about Mercury’s evolution, and also discover just how it can be related to planetary evolution overall. All of the findings detailed by the scientists who were apart of the MESSENGER mission can be found online through the Science journal.